/Engine/Source/Runtime/UMG/Public/Blueprint/WidgetBlueprintLibrary.h
Find all widgets in the world with the specified interface. This is a slow operation, use with caution e.g. do not use every frame.
static void GetAllWidgetsWithInterface ( [UObject](API\Runtime\CoreUObject\UObject\UObject) * WorldContextObject, [TArray](API\Runtime\Core\Containers\TArray)< [UUserWidget](API\Runtime\UMG\Blueprint\UUserWidget) * > & FoundWidgets, [TSubclassOf](API\Runtime\CoreUObject\Templates\TSubclassOf)< [UInterface](API\Runtime\CoreUObject\UObject\UInterface) > Interface, bool TopLevelOnly )